A wide variety of roller cone drill bits have previously been used to form wellbores in downhole formations. Such drill bits may also be referred to as “rotary” cone drill bits. Roller cone drill bits frequently include a bit body with three support arms extending therefrom. A respective cone assembly is generally rotatably mounted on each support arm opposite from the bit body. Such drill bits may also be referred to as “rock bits”.
Examples of roller cone drill bits satisfactory to form wellbores include roller cone drill bits with only one support arm and one cone, two support arms with a respective cone assembly rotatably mounted on each arm and four or more cones rotatably mounted on an associated bit body. Various types of cutting elements and cutting structures such as compacts, inserts, milled teeth and welded compacts have also been used in association with roller cone drill bits.
Cutting elements and cutting structures associated with roller cone drill bits typically form a wellbore in a subterranean formation by a combination of shearing and crushing adjacent portions of the formation. The shearing motion may also be described as each cutting element scraping portions of the formation during rotation of an associated cone. The crushing motion may also be described as each cutting element penetrating or gouging portions of the formation during rotation of an associated cone.
Roller cone drill bits having cutting structures formed by milling steel teeth are often used for drilling soft formations and some harder formations. Roller cone drill bits having cutting elements and cutting structures formed from a plurality of hard metal inserts or compacts are often used for drilling both medium and hard formations. Roller cone drill bits are generally more efficient in removing a given volume of formation by shearing or scraping as compared with crushing or penetration of the same formation. It is generally well known in the roller cone drill bit industry that drilling performance may be improved by varying the orientation of cutting elements and cutting structures disposed on associated cone assemblies.